According to British media reports, United will have to pay £22.5 million ($28 million) — as the club are still in the Champions League — to sever the ties with the 55 year-old Portuguese.
Mourinho, who had coached Chelsea, Porto, Real Madrid is the third coach to be fired at Old since Sir Alex Ferguson retired in 2013 after 27 years in charge.
The job has been a most difficult one since then.
Mourinho, in his third season, was sacked as the great club languished in sixth in the Premier League, a massive 19 points behind rivals and leaders Liverpool.
Mourinho’s last duty was humiliating as the club suffered a 3-1 drubbing by Premier League league leaders Liverpool on Sunday.
His downfall was predictably accurate after the match as the club owners got tired with his excuses.
Came the club’s bombshell.
Manchester United announces that manager Jose Mourinho has left the club with immediate effect,” a club statement said.
“The club would like to thank Jose for his work during his time at Manchester United and to wish him success in the future.
“A new caretaker manager will be appointed until the end of the current season, while the club conducts a thorough recruitment process for a new, full-time manager.”
Carrick is favoured for the caretaker role having become part of the coaching staff this season.
In the longer term former Real Madrid coach Zinedine Zidane has been linked to the club and Tottenham Hotspur manager Mauricio Pochettino could also be a name in the frame.
Mourinho’s reign had started well enough with the League Cup and the Europa League trophies but neighbours Manchester City’s dominance over them in the league has hurt.
The wound went even deeper for Mourinho as City are managed by Pep Guardiola, who got the better of him when he managed Barcelona and Mourinho was at Real Madrid.